As both self-driving vehicle algorithms and Advanced Crash Avoidance Technologies (ACATs) are being developed by many manufacturers, the need to test these vehicles and technologies escalates. Full-scale test methodologies need to minimize hazards to personnel and damage to equipment. Accordingly, Guide Soft Target (hereinafter GST) systems provide a way to safely test subject vehicles in crash avoidance technologies.
GST systems act as safer surrogates for real cars and trucks during testing. In a GST system, a soft collision partner (hereinafter Soft CP) may be mounted atop a Dynamic Motion Element (hereinafter DME), which may be a Low-Profile Robotic Vehicle, or LPRV. The DME is driven, moving the Soft CP body, so that while in motion, the Soft CP may be detectable as a moving vehicle by the subject vehicle under test. ACATs on a subject test vehicle may be tested by observing how the subject vehicle responds to the GST. In thoroughly testing the crash avoidance technology, the GST system may be used in a wide variety of real-world scenarios that could result in collisions between the subject test vehicle and the GST. These tests can be used to check whether the subject test vehicle can avoid the Soft CP, and evaluate the crash avoidance technology based on measured parameters such as response time, braking distance, minimum distance between the subject vehicle and the Soft CP, etc. Compared to subject vehicle collisions with another vehicle, use of the Soft CP and DME is less hazardous for testing personnel, and minimizes the damage that the collision causes to the subject vehicle.
Prior art for Soft CPs such as a “balloon car,” a rear-end target specified by the National Highway Traffic Safety Administration (NHTSA), and a cushioned crash target provided by Anthony Best Dynamics (ABD) each has its deficiencies. The balloon car is prone to damage, and is particularly prone to bursting when it is impacted at higher speeds. Aerodynamic flutter can also confuse the sensors on the subject vehicle, and becomes a problem at higher speeds. The NHTSA car-rear target can only be used for testing rear-end collisions, and is not suitable for testing any other type of collision, so it has limited applications. Finally, an ABD soft CP has a relatively large drive system that cannot be driven over or through. The ABD soft CP also cannot be tested at speeds substantially higher than 50 kilometers per hour because the momentum from a higher speed impact would cause damage, which also limits its usefulness in generating data.
U.S. Pat. No. 8,428,863 discloses a Soft CP comprised of a plurality of panels, where the novelty is that both the Soft CP body and the DME can be driven over or through. The material used for the Soft CP body would cause minimal to no damage to a subject test vehicle. When fitted with an exterior skin, the geometry of the Soft CP bodies resembles that of a full-size vehicle. Furthermore, the Soft CP body is made from modular panels that can be easily reassembled and reused after impact. Such a Soft CP is thus more practically suitable for testing ACATs across a range of conditions, including the speed, the place and the angle of the impact.
However, because GST systems depend on measurements and the reliable and accurate detection of the Soft CP body as a vehicle by crash avoidance technologies on the subject vehicle, it is desirable that the Soft CP has a radar signature close to that of real vehicles. Otherwise, the testing would not be realistic. That is, there would be many more collisions that result, because the subject vehicle would not detect the Soft CP body as a moving vehicle and might not try to avoid it.
One problem that could cause the Soft CP to reflect a radar signature substantially different from the radar signature of a real vehicle happens when radar enters the Soft CP, reflects internally, and exits the Soft CP after experiencing the many reflections inside the Soft CP. In that case, since the radar signature of the Soft CP would be different from a more typical real vehicle radar signature, the subject vehicle may fail to recognize the Soft CP as a moving object, or, even worse, mistakenly see multiple vehicles at other positions due to the radar energy reflecting inside the Soft CP before returning to the radar sensor.
Another potential problem might occur at other wavelengths, such as in the visible and infrared (VIR) spectra, where the subject vehicle may mistakenly believe there is no obstacle ahead because the reflected VIR signature may not match the signature that the subject vehicle might expect. The object of the present invention is to address such problems, reduce errors and improve accuracy and operations of the GST system by improving the radar signature and/or other signal signatures to match the signature(s) of a real vehicle.